Abstract: In the permanent magnet synchronous motor（PMSM） regulation system, an excellent speed controller should have both tracking performance and anti-disturbance performance. With the advantages of fast response and strong robustness, nonlinear control is more suitable for the design of speed controller, but the traditional sliding mode control（SMC） has serious chattering problem. The adaptive Super-twisting algorithm belongs to a second-order SMC, as it could enable to converge the state variables of the phase trajectory to the origin in a series form, and adjust the controller gain online, so chattering could be effectively weakened. An adaptive Super-twisting algorithm is used to design the speed controller, and its stability is proved by the Lyapunov function. The experimental results show that the proposed controller has good tracking performance and anti-disturbance performance, and can reduce the current rippleto weaken chattering.